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PCM Connector: Black (C4) 1998-99
This section contains the C4 (Black) PCM connector pin outs. To navigate to a different PCM connector, use the links below:
| C4 (Black) PCM 24 Pin Connector | ||
|---|---|---|
| Pin | Wire Color | Description |
| 1 | Dark Green w/ White stripe | Fuel Pump Relay Control |
| 2 | --- | Empty |
| 3 | Dark Green w/ White stripe | Vehicle Speed Sensor (VSS) Output Signal (TCCM, Radio, Cruise) |
| 4 | Dark Green | Vehicle Speed Sensor (VSS) Output Signal (Speedometer) |
| 5 | Brown w/ White stripe | Malfunction Indicator Light (MIL) ...Check Engine Light |
| 6 | --- | Empty |
| 7 | Dark Green | Inlet Air Actuator (Recirculation Door Motor) Control |
| 8 | --- | Empty |
| 9 | Dark Blue | Auxiliary Electric Cooling Fan |
| 10 | Purple | Brake Switch Signal |
| 11 | Purple | Serial Data (Class 2) |
| 12 | Black | Dual Fuel Module Return |
| 13 | Brown | 12 Volt Ignition Feed |
| 14 | --- | Empty |
| 15 <-> | --- | Empty (1998 Only) |
| 15 <-> | Tan w/ Black | Shift Light (Manual Transmission -1999 Only) |
| 16 | Red | EGR Valve Solenoid Control |
| 17 | --- | Empty |
| 18 | Pink | 12 Volt Ignition Feed |
| 19 | Black w/ White stripe | 4WD Engaged Signal (Wheel Lock Input) |
| 20 | White | EGR Valve Solenoid Control |
| 21 | --- | Empty |
| 22 <-> | --- | Empty (1998 Only) |
| 22 <-> | Brown w/ White stripe | CPP Switch Signal (Manual Transmission -1999 Only) |
| 23 | Gray w/ Black stripe | Transfer Case High Low Switch |
| 24 | Light Blue w/ Black stripe | Cruise Engaged Signal |
Safety Precautions
Here are some very important safety precautions when testing the wires coming out of the PCM connectors.
- If one or any of the wires on your GM vehicle DO NOT match the color stated in the Pin Out Charts, then you should not use the Pin Out Charts in this article. Why? Because this is the clearest indication that these ARE NOT the Connector Pin Out Charts for your particular vehicle.
- Never probe the front of the connector.
- You should use a wire piercing probe and probe the wire a few inches away from the connector.
- To see what this tool looks like: Wire Piercing Probe.
- You should use a back probe.
- You should use a wire piercing probe and probe the wire a few inches away from the connector.
- This is a FLASH unit and requires reprogramming if replaced with a new one or used one.
- Read the Disclaimer.
If this info saved the day, buy me a beer!
